Doraemon, Nobita and the Castle of the Undersea Devil (2026): Release Date, Story, Cast & Everything You Need to Know

If you grew up anywhere near a TV in the last few decades, that cheerful blue robotic cat and the hopeless, big-hearted kid in the yellow shirt probably hold a ridiculously special place in your memory. There is just something about Doraemon and the Undersea Devil that instantly takes you back to simpler times—sitting on the living room floor, eating snacks after school, and wishing with all your heart that you had a secret 4D pocket attached to your stomach

And honestly? That magic hasn’t gone anywhere.

In 2026, the franchise is back on the big screen with its 45th movie: Doraemon the Movie: New Nobita and the Castle of the Undersea Devil.

If that title, The Undersea Devil, gave you a sudden hit of nostalgia, you aren’t crazy! It is a fresh, visually stunning remake of the classic 1983 film that so many of us obsessed over as kids. Except this time, the animation is mind-blowing, the sound design makes your chest rumble, and the emotional hits pull straight at your heartstrings.

If you’re wondering what this new chapter is all about, whether it’s worth watching, or when it hits theaters near you—pull up a chair. Here is everything you need to know, plain and simple.

Quick Movie Snapshot

If you just want the fast facts before we get into the fun stuff, here’s the breakdown:

• Movie Title:Doraemon the Movie: New Nobita and the Castle of the Undersea Devil
• Japanese Title: 映画ドラえもん 新・のび太の海底鬼岩城 (Eiga Doraemon Shin Nobita no Kaiteiki Ganjō)
• What is it? The 45th feature film in the franchise (a total reimagining of the 1983 classic)
• Original Creator: Fujiko F. Fujio
• Director: Tetsuo Yajima
• Screenplay: Isao Murayama
• Animation Studio: Shin-Ei Animation
• Theme Song:“Honto” by the Japanese rock band sumika
• Japan Release Date: February 27, 2026
• Coolest Tech Upgrade: It’s the first Doraemon movie ever made for 4DX and MX4D motion theaters!

The Plot: How an Argument Over Vacation Turned Into an Ocean Odyssey

1. The Ultimate Friend Group Debate

We have all been in this exact situation. It’s summer break, you’re hanging out with your friends, and nobody can agree on what to do.

Gian and Suneo are dead set on going to the rugged mountains to camp out like tough adventurers. Nobita and Shizuka just want to kick back and relax on a sunny beach. Words get thrown around, nobody wants to compromise, and every decent campsite is already fully booked anyway. The Undersea Devil changes everything when their plans take an unexpected turn.

Naturally, Nobita does what Nobita always does: he runs home crying to Doraemon, begging for a miracle.

And Doraemon, being the absolute legend he is, comes up with a wild solution: “Why choose between the mountains and the sea when we can camp on the mountains under the ocean?”

2. Diving 10,000 Meters Down

At first, it’s a total dream vacation. They set up an underwater tent, swim through glowing coral reefs, play games, and discover sea life that no land human has ever seen. But as they venture deeper toward the Mariana Trench and explore ancient, sunken wooden ships, things take a very sudden, serious turn.

3. The Secret Civilization Below the Waves

While exploring the dark ocean floor, they run into El, a young knight from the Mu Federation.

Turns out, Mu is a massive, secret, ultra-advanced underwater nation known as The Undersea Devil, that has lived beneath the Pacific Ocean for thousands of years. But there’s a catch: the ocean people hate land humans. They’ve spent centuries watching us pollute their waters and fight wars on the surface, so their military immediately arrests Nobita and the gang.

However, Nobita’s total lack of bad intentions, Shizuka’s warmth, and Doraemon’s honesty slowly break down El’s walls. El realizes these surface kids aren’t monsters—and as luck would have it, he needs their help to save the entire planet.

4. A Cold Machine and a Ticking Clock

After mistaking a natural underwater volcanic eruption for a surface attack, Poseidon wakes up and triggers an automated countdown to launch global destruction weapons.

With time running out, Nobita, Doraemon, Shizuka, Gian, Suneo, and their trusty Buggy team up with El to sneak into the Bermuda Triangle, shut down Poseidon, and stop the end of the world.

Meet the Characters (And the Amazing Voices Behind Them)

The vocal cast is what gives this movie its beating heart. The regular iconic gang returns, joined by some fantastic guest stars:

The Main Crew

• Doraemon (CV: Wasabi Mizuta): As energetic, warm, and protective as ever. Wasabi Mizuta’s voice work continues to be the comforting glue holding the whole group together.
• Nobita Nobi (CV: Megumi Ōhara): He whines, he panics, and he complains about walking—but when his friends or the ocean people are in danger, Nobita’s emotional bravery steals the show.
• Shizuka Minamoto (CV: Yumi Kakazu): The real emotional bridge of the story. Shizuka’s kindness toward the undersea people—and especially toward the stubborn Buggy—is what turns enemies into family.
• Gian / Takeshi Gōda (CV: Subaru Kimura): He might be the neighborhood bully on land, but deep beneath the sea, Gian is the big brother who will throw himself in front of any danger to protect his crew.
• Suneo Honekawa (CV: Tomokazu Seki): Terrified of the dark ocean, constantly complaining, but ultimately showing up when his friends need him most.

The Ocean Inhabitants

• El (CV: Shōya Chiba): A brave young soldier from Mu who has to unlearn his prejudices against land-dwellers after seeing Nobita’s kind heart.
• The Underwater Buggy (CV: Ryō Hirohashi): Bring tissues. Seriously. Buggy is a grumpy, stubborn little vehicle who talks back to everyone, but his relationship with Shizuka will break your heart and put it back together again.
• Poseidon (CV: Takayuki Sugō): A chillingly calm AI antagonist who doesn’t hate humanity—he’s just blindly executing an ancient code. That cold logic makes him genuinely scary.

Behind the Scenes: A Director’s Passion Project

Stepping into the director’s chair for a franchise as massive as Doraemon isn’t easy, but Tetsuo Yajima was born for this. Having worked on fan-favorite films like Underworld (2007) and Earth Symphony (2024), Yajima brought a huge sense of childlike excitement to the project.

Here is what Director Yajima had to say about making the movie:

“10,928 meters—the deepest point ever reached by mankind. Let’s venture further with Doraemon and his friends! Certainly there are creatures and sceneries waiting for us that no one has ever seen before. Aren’t you excited just thinking about it? The choices and decisions they face there may trouble them at times. But hidden among those will surely be ‘unexpected answers.’ To a deep-sea world no one has ever seen before—the Undersea Devil—we look forward to the day we can experience it together on the screen.”

Screenwriter Isao Murayama, who has been writing TV episodes for the show since 2023, managed to keep all the soul of Fujiko F. Fujio’s original 1983 vision while making the dialogue feel completely natural and modern for today’s kids (and adults!).

Box Office Boom & When You Can Watch It

When the movie hit Japanese theaters on February 27, 2026, The Undersea Devil blew up immediately. It sat comfortably at the #1 spot at the Japanese box office for six weeks straight, pulling in over $25.88 million.

International Release Rollout

If you live outside of Japan, here is when the ocean adventure travels around the globe:

• Japan: February 27, 2026
• Vietnam: May 22, 2026
• South Korea: July 1, 2026
• Indonesia: July 15, 2026
• India: October 2, 2026 (In Hindi, Tamil, and Telugu via PVR INOX Pictures & TV Asahi)
• France: October 7, 2026
• Thailand: October 8, 2026

The release in India on October 2, 2026 of The Undersea Devil is a massive deal for fans. Releasing on a national holiday in three major languages means families across the country can head to theaters together to experience it on the big screen.

1983 vs. 2026: Why You Need to See the Remake

If you watched the original cartoon back in the day, you might be asking: Is this just a lazy cash grab?

Not at all. In fact, it might be one of the best remakes the franchise has ever done:

1. Visually Unreal Underwater Worlds: Modern lighting techniques make the ocean look mind-blowing. The glowing bioluminescence of Mu feels like a dream, while the dark, rusty trenches near Atlantis feel genuinely heavy and dangerous.
2. Smarter, Modern Themes: The 1983 film was very focused on Cold War nuclear fears. The 2026 version updates this idea to talk about rogue AI, automated warfare, taking care of our oceans, and learning to trust people who seem different from us.
3. The Emotional Hits are Stronger: The bond between Shizuka and the Underwater Buggy gets way more breathing room, making the final third of the movie a total emotional powerhouse.